The present invention relates to a connector comprising a plug and a jack. More particularly, the invention relates to an improved connector having polarity for preventing a connection when the plug or the jack is reversed.
In a connector having polarity, a polar key projects from an inner side wall of a plug. A guide groove is formed on a side wall of a jack at a position corresponding to said polar key. In such a construction, the jack can be connected to the plug when it is in a normal position, by inserting the polar key into the guide groove. On the other hand, the jack is prevented from being inserted when said jack is in a reversed position, i.e. when it is turned to a position at an angle of 180.degree. from the normal position, in an inlet front surface of the jack, since the polar key of the plug abuts against the front surface of the jack. In a prior art connector having polarity, the top end of the polar key is rounded in order to achieve a smooth insertion of the polar key into the guide groove. Therefore, even when the jack is in the reversed position, said jack can be forced to penetrate into the plug, pushing the side wall thereof open, by an excessive force for insertion. In such a case, the desired function of the polar key, which is to prevent erroneous connection of the jack and the plug, cannot be achieved.